You may need to download your graphics driver from the vendor, and boot the red hat kernel that works with your graphics card. Did you do updates from red hat prior to the display not working? If you did updates, you kernel can change and therefore your graphics card may not work with the updated kernel.

Please note, this is *gpm* not gdm. GPM means "Graphical Pointer Mouse".And
it really doesn't matter which version "KDE or GNOM" you are using, "xfs"
will handle that.

Till redhat linux enterprise 4, these commands were very famous. Also, if
you had sit for RHCE exam that time, you may also know about that. Also to
clarify more, one of the compulsory question was based on those two concept.

In enterprise 5.1 and later, graphics was handled smoothly and use of those
commands reduced.

And about chkconfig, your option is also right.

Last of all, you have to restart both the services and also need to check
whether these services are working on runlevel. My previous command will do
that. I have executed two commands in single line.